jshint error with regular expression

Question

Does anyone know why jsHint says this regular expression has a "Bad Escapement"?

var regexp = new RegExp('^http(s)?:\/\/([a-z]+\.)?(' + this.opts.domain + ')', 'ig');

It's complaining about the escaped period \\.

The regex still works without escaping the period. My goal is to find if a URL contains a given domain name, http://rubular.com/r/5U7kVjhleu

Answer 1

如果从字符串构造正则表达式，则需要将反斜杠加倍（并且不需要转义斜杠）：

var regexp = new RegExp('^http(s)?://([a-z]+\\.)?(' + this.opts.domain + ')', 'ig');